Initially made of metal sheets, such as used in the Lhermite process, these reinforcements have seen their composition evolve in the last few decades following the appearance of replacement materials for metal sheets. Reinforcements based on composites in the form of bonded plates (see, for example, document FR-A-2594871) or bonded fabrics (see, for example, document EP 0 799 951) are now commonly used.
Reinforcements based on composites have many advantages, in particular linked to their ease of use and to their ability to be applied to various surfaces. They improve, for example, very substantially, the dynamic behavior of the reinforced structure.
Use may advantageously be made of reinforcements of elongated shape comprising continuous fibers combined with a polymer matrix, manufactured for example by pultrusion or by extrusion and the cross section of which is substantially constant along a longitudinal direction. These reinforcements of elongated shape may advantageously be in lamellar form so as to provide a broad bonding surface area. These reinforcements are, for example, positioned on a face in tension of a structural element made of reinforced or prestressed concrete so as to enable a reinforcement in tension. These reinforcements may also have the shape of long cylinders commonly known as rods.
An example of a reinforcement in lamellar form is sold by the company Freyssinet under the commercial reference FOREVA® LFC.
By way of example, such elongated reinforcements in lamellar form may have a width of 50, 80, 100 or 150 mm and a thickness of 1.2 mm.
Still by way of example, reinforcements of elongated shape are constituted of carbon fibers impregnated by an epoxy matrix. Such reinforcements may be manufactured by pultrusion or by extrusion.
Such reinforcements of elongated shape, although very commonly used for reinforcing construction structures, nevertheless have certain drawbacks. In particular, it is observed that it is difficult to optimize the binding configuration of such reinforcements with a portion of the structure to be reinforced.